Effect of prebiotic xylooligosaccharides on growth performances and digestive enzyme activities of allogynogenetic crucian carp (<Emphasis Type="Italic">Carassius auratus gibelio</Emphasis>)

The effect of prebiotic xylooligosaccharides (XOS) on the growth performance and digestive enzyme activities of the allogynogenetic crucian carp, Carassius auratus gibelio, was investigated. XOS was added to fish basal semi-purified diets at three concentrations by dry feed weight: diet 1, 50 mg kg⁻¹; diet 2, 100 mg kg⁻¹; diet 3, 200 mg kg⁻¹, respectively. Twelve aquaria (n = 20) with three replicates for each treatment group (diets 1–3) and control treated without XOS were used. Weights of all collected carp from each aquarium were determined at the initial phase and at the end of the experiment, and the carp survival was also determined by counting the individuals in each aquarium. After 45 days, there were significant differences (P < 0.05) in the relative gain rate (RGR), and daily weight gain (DWG) of diets 1–3 were compared with the control. However, the survival rate was not affected (P > 0.05) by the dietary treatments. For enzymatic analysis, dissection produced a crude mixture of intestine and hepatopancreas of each segment to measure. The protease activity in the intestine and hepatopancreas content of fish in diet 2 (487.37 ± 20.58 U g⁻¹ and 20.52 ± 1.93 U g⁻¹) were significantly different (P < 0.05) from that in the control (428.13 ± 23.26 U g⁻¹ and 12.81 ± 1.52 U g⁻¹) and diet 3 (428.00 ± 23.78 U g⁻¹ and 14.04 ± 1.59 U g⁻¹). Amylase activity in the intestine was significantly higher for diet 2 compared to diet 1 and the control. As for amylase in the hepatopancreas, assays showed higher activity in diet 2 (P < 0.05) compared to the rest.     

抗生素在海链藻培养过程中作用的研究

探讨了海链藻对四种抗生素(头孢唑林钠、哌拉西林钠、盐酸林可霉素、硫酸阿米卡星)的敏感性研究。研究表明,盐酸林可霉素促进海链藻生长的最佳浓度应该为5 mg/L,哌拉西林钠促进海链藻生长的最佳浓度应该为1 mg/L,而硫酸阿米卡星、头孢唑林钠促进海链藻生长的最佳浓度则都为10 mg/L。     

A comparison of the growth and survival of two freshwater crayfish species, Astacus leptodactylus Eschscholtz and Pacifastacus leniusculus (Dana), under different temperature and density regimes

Growth experiments carried out with two juvenile crayfish species, Astacus leptodactylus Eschscholtz and Pacifastacus leniusculus (Dana), at different temperatures and densities highlighted the problem of cannibalism under conditions aimed at intensifying crayfish production. Cannibalism proved to be much lower in A. leptodactylus than P. leniusculus, suggesting that the former might be the better candidate for astaciculture. In the first of two population survival trials, A. leptodactylus showed a higher survival rate than P. leniusculus, with 26% of P. leniusculus surviving in the first replicate, compared to 42.3% of P. leniusculus, and 40.76% surviving in the second replicate, compared to 47.6% of P. leniusculus. The same trend was observed in the second experiment, with P. leniusculus showing survival rates of 48.5 and 55.3% (first and second replicates, respectively) in comparison to 65.2 and 68.2%, respectively, for A. leptodactylus. It is therefore highly likely that if P. leniusculus were to become established in Turkey, it would outcompete the native A. leptodactylus even if it were not to be devastated by the crayfish plague that has decimated the native species. The experiments also highlighted the problem of differential growth, with some juveniles hardly growing at all while others reached a relatively large size. The range in carapace length (CL) was 9–18 mm for A. leptodactylus and 8.5–18.5 mm CL for P. leniusculus at the end of the first experiment. While both species grew quickly, P. leniusculus hatched earlier, giving it an advantage over A. leptodactylus; consequently, by the end of the summer, the juveniles of the former were larger than those of A. leptodactylus. Specific growth rate values showed that the juveniles of the two species had similar growth rates. The results also revealed that growth was not significantly affected by density in both species at 15°C, but at 25°C, growth was significantly better at a density of 234 juveniles m⁻² than at 468 juveniles m⁻², and better at 468 juveniles m⁻² than at 937 juveniles m⁻² (P < 0.01 and P < 0.001, respectively). We conclude that P. leniusculus is a good candidate for aquaculture as it has a rapid growth rate and early hatching and maturity; however, its aggressive behavior may make it a less attractive proposition than A. leptodactylus, which is also fast growing but less aggressive. This study is a part of PhD study of M.M. Harlıoğlu, who is supported by Fırat University Elazığ, Turkey.     

Growth and water quality for growing-out of juvenile spotted Babylon, Babylonia areolata, at different water-exchange regimes in a large-scale operation of earthen ponds

Growth and water quality for growing-out of juvenile spotted Babylon, Babylonia areolata, were determined at three water-exchange regimes of 7-, 15- and 30-day intervals in large-scale operation of earthen ponds over a 5-month period. Results showed that growth was significantly different among the water-exchange treatments (P < 0.05). The higher body weight gains and shell length increments were observed in snails held at water exchange of 7- and 15-day intervals when compared with those held at water exchange of 30-day intervals. At the end of the experiment, average body weight gains were 4.22, 3.73 and 2.77 g for snails held in water-exchange treatments of 7-, 15- and 30-day intervals, respectively, and 16.63, 15.04 and 13.78 mm for those of shell length increments, respectively, The average final survivals were 83.60, 80.90 and 74.20% for snails held in water-exchange treatments of 7-, 15- and 30-day intervals, respectively. Seawater temperature, salinity, pH, dissolved oxygen, nitrite–nitrogen and ammonia–nitrogen had gradually changed throughout the culture period for all water-exchange treatments. With one exception, the total alkalinity showed the greatest changes during the culture period for all water-exchange treatments ranging from 58.67–97.50 mg/l.     

不同生长阶段斑节对虾消化酶活性变化

通过对斑节对虾不同生长阶段蛋白酶、脂肪酶及淀粉酶活性变化的分析,探讨了斑节对虾在生长过程中对蛋白质、脂肪和碳水化合物的消化利用。结果表明,根据消化酶活性,可将斑节对虾生长分为两个阶段。第1阶段,在体长10～12.5 cm阶段之前,随着个体的增大蛋白酶和脂肪酶活性不断升高;第2阶段,在12.5 cm之后,蛋白酶和脂肪酶活性呈现出一定程度的下降。肝胰腺、胃、肠3种不同消化器官的消化酶活性在不同生长期也不一致,大致上蛋白酶活性从高到低依次为:肝胰腺>胃>肠;脂肪酶活性:肠>肝胰腺>胃;淀粉酶活性:肠>胃>肝胰腺。     

Summer mortality of hatchery-produced Pacific oyster spat (Crassostrea gigas). I. Estimation of genetic parameters for survival and growth

The multidisciplinary project “MOREST” aims to improve our understanding of causes of summer mortality in Crassostrea gigas juveniles in France and to reduce its impact on oyster production. As part of the MOREST project, 43 full-sib families nested within 17 half-sib families were produced, planted out and tested in 3 sites during summer 2001 to assess to what extent genetic variability exists for this trait. A strong genetic basis was found for survival as narrow-sense heritability estimates ranged from 0.47 to 1.08, with higher values in sites where summer mortality was higher. Genetic correlations across sites were positive and very high for survival, indicating no genotype by environment interaction. In contrast, lower genetic variation was observed for growth in all sites. Finally, genetic correlations between growth and survival were low, in all sites. Selective breeding in a single site should therefore be an efficient means of improving survival in oysters less than one year old along the French Atlantic and Channel coastlines with only very limited effects on growth. As yield mostly depends on survival and growth, this approach should significantly improve harvestable yield. Possible reasons why a high genetic variance for survival appears to be maintained in wild populations are discussed.     

鸭绿江上游花羔红点鲑的年龄_生长_食性和繁殖的研究

花羔红点鲑的鳞片年累特征为疏密一切割混合型。体长和体重关系密切,属均匀性生长类型。主要以水生昆虫为食,对食物有明显的选择性;主要摄食季节为夏秋两季,但可终年摄食。雌雄鱼几乎２＋龄达到性成熟,产卵期为１０￣１１月,绝对繁殖力为２８０￣５００粒,每年产一次卵,属秋季产卵类型。产卵场底质为石砾,水深５０￣７０ｃｍ,水流速度１．５￣２．０ｍ／ｓ,水温一般为５￣８℃。     

Evaluation of VI-alpha and PIT-tagging of the seahorse <Emphasis Type="Italic">Hippocampus abdominalis</Emphasis>

The suitability of visible implant alphanumeric (VI-alpha) and passive integrated transponder (PIT)-tagging to individually identify seahorses (Hippocampus abdominalis) was assessed in two trials. For each trial, 24 seahorses were tagged and mortality, growth, tag retention and tag visibility/readability assessed, together with 24 control seahorses, over a period of 3 months. For VI-alpha tagging, a single tag was inserted under the skin between the first two anterior lateral tail rings of the seahorses. There was no difference in final seahorse length, wet weight, or mean SGR in tagged seahorses, compared with control seahorses, after 3 months. Tag retention was 100%, as was survival, in both treatments. Tag detection with the naked eye was generally poor but improved using LED blue light. However, readability of tag codes was highly variable and insufficiently reliable for VI-alpha to be suitable for identification of individual seahorses. In PIT-tagged seahorses, a single FDX-B transponder was inserted into the abdominal cavity of seahorses. There was also no difference in final seahorse length, wet weight, or mean SGR, compared with control seahorses, after 3 months. Tag retention was also 100%, as was survival in both treatments. Readability of transponders was reliable and quick using a compact reader. PIT-tagging is considered suitable for individual identification of large H. abdominalis.     

1956—2010年辽西地区玉米气候适宜度时空分布特征

以玉米气候适宜度模型及辽西地区4市8站近50 a(1956—2010年)逐日气象数据为基础,利用空间插值、经验正交函数分析方法(EOF)和小波变换分析方法对玉米全生育期及各主要生育时期气候适宜度的时间变化和空间分布特征进行分析,研究气候变化过程中辽西地区农业气候资源对玉米生长的适宜程度的变化特征。结果表明：1)近50 a,辽西地区玉米全生育期的降水、日照及综合气候适宜度呈逐年下降趋势,除开花期综合气候适宜度呈上升趋势外,播种、出苗、成熟期综合气候适宜度均呈下降趋势;2)在空间分布上,辽西玉米全生育期的温度适宜度、日照适宜度,播种、成熟期的综合气候适宜度分别表现出由南向北、由西向东、由西向东南和东北、由东北向西南递增,而出苗期综合气候适宜度表现为由西北向东南和东北递减;全生育期的降水适宜度、综合气候适宜度和开花期的综合气候适宜度由北向南均呈现“低－高－低－高”的带状分布特征,播种、出苗和开花期限制因素分别为降水、日照和日照;3)EOF 分析发现,辽西地区玉米全生育期综合气候适宜度距平百分率在空间上表现为西南向东北微幅递减;在时间上,小波分析发现辽西玉米综合气候适宜距平百分率第1特征向量的时间系数存在14~30 a、8~14 a、3~7 a 的3类尺度的震荡周期。     

土壤质地对柱花草生长发育、生物量及土壤肥力变化的影响

采用大田试验的方法,在云南省元谋县小雷宰流域内壤土、砂壤土和重壤土3种质地土壤上,以热研5号柱花草为材料,研究土壤质地对柱花草生长发育、生物量及土壤有机质、有机碳、全氮和全磷的影响。试验结果表明:3种土壤质地上种植柱花草,柱花草地上部和地下部生长量和生物量表现幼苗期增加缓慢,而分枝期后增加快的趋势。壤土耕性好,兼有砂土和重壤土的优点,有利柱花草地上部分的生长发育,柱花草地上部生长量、生物量及改善土壤肥力方面显著高于重壤土。砂壤土有利于柱花草根系向深层土壤生长,柱花草地下部生长量、生物量及根瘤显著高于种植在重壤土。在3种土壤质地种植柱花草后,土壤有机质、有机碳、全氮和全磷均有上升趋势。综合而言,通气性和保肥保水能力居中的壤土更适合柱花草的生长发育及干物质的积累。